> Or just ask yourself this: if airfoils *must* be more curved on
> top, doesn't this prove that symmetrical airfoils cannot work,
> and that upside-down flight is impossible?
That's not true, even by the faulty lifting theory. The essential
requirement (of the bad theory) is that the path length over the wing has
to
be longer than the path length under it. No matter the airfoil section or
camber (for real airfoils, anyway), you can screw with the angle of attack
enough to move the stagnation point around so that the flow length over
the
top is longer.
Symmetrical airfoils don't generate any lift unless they're at positive
angle of attack (i.e. the stagnation point is below the geometric
"front").
Tom.
